Recording system



Jan 3, 1928.

- ll GREEN RECORDING SYSTEM Filed Jan. 50, 1925 BY W a ATTORNEY Patented Jan. 3, 1928.

1,654,645- U-NITEDISTATES PATENT OFFICE.

IRVING WALTER GREEN, or CRANFORD, ew JERSEY. Ass'reNoR T0 AMERICAN TELE- rnonn AND TELEGRAPH COMPANY, A CORPORATION or new YORK.

RECORDING SYSTEM.

Application filed January 'tems, and particularly to arrangements in such systems for indicating the amount of energy entering the system. One of the ob- ]ects of the invention is to provide arrangements in telephone circuitst'or securing suthcient energy in the currents of said circuits for satisfactory recording.

In the former arrangements ot such sys tems the amplifierwas connected across the.

receiver of the telephone circuit, the current in the telephone circuit flowing through the receiver and the input circuit of the amplifier. The output'circuit of the amplifier was connected to the sound box or inscribing element of therecorder. \Vith such arrangements the subscriber had no in ans for indicating whether the gain of the amplifier was sutlicient for good recording results. One of the objects of this invention is therefore to provide means'whereby the subscriber may determine whether the gain of the amplifier is sufiicient for proper recording. I

In order that the invention may be more clearly understood, attention is hereby directed to the accompanying drawing which forms a part otthe specit'ication.

Referring to the drawing, the usual apparatus ot' a subscriber's anti-side tone telephone set, in which the telephone trans mitter has little effect on the receiver, and vice versa, is indicated as connected to the conductors of line 1. 5 represents the re ceiver of line 1. The amplifier 4 connectsthe telephone circuit with the recorder 8. The potentiometer 2 may be adjusted by the movable arm 3.

. 3 Sound impinging upon the diaphragm oh the transmitter at the distant station tinctuates the current. over the conductors oi line 1. The hell 9 is of such high impedance that its presence in the line does not appreciably at'l'ect transmission. However, when the receiver 5 is on the hook ll, the transmitter circuit and the receivercircuit are both open, thereby conserving the energy of "the electrical sources when not required, and preventing the ringing current from flowing throtwh the receiver. iVhen the receiver 5 is ofi tie hook, the ringer 9 is in series with the condenser 12, giving a closed circuit to. the alternating current used for ringing, but an open circuit to the direct cur-' rent from the source of current supply used for signaling the operator.

30, 1925. Serial No. 5,869.

The potentiometer 2 and the amplifier 4 are arrangedun the leads of. the receiver 5 through a resistance or other network 6 having a transmission loss which may be made equal to the maximum gain of .the amplifier 4. The gain of the amplifier is adjusted-by movingthe-arm t of the in'itentiometer t1; and the sound box or inscribing element: 7 is connected directly to the output circuit of the amplifier I i l Vith the arrangement described 'thesubscriber may regulate the gain of the amplifier 4 by moving the arm 3 ofthe potentiometer so as to obtain satisfactory recording. F or instance, assuming that the amplifier has a maximum gain of twenty miles and that the resistance 6 has a transmission loss which is equal to the maximum gain of the amplifier, twenty miles, and assuming that the gain of the amplifier is adjusted to the position for the twenty mile gain, this would result in a level at Z), the output circuit of the amplifier 4, and at (Z, the sound -bo:t or inscribing element-'7 of the recorder 8, twenty miles inexcess otthe level applied at a, the input circuit of the amplifier 4. The level at c, the receiver 5, would be twenty miles less than the levels at h and (Z,- or, for the case assun'i'ed, the level at 0 would be the same as the level at a. For all gains at which the amplifier at may be set, the level at (I, the recorder, would always be in excess of the level at c, the receiver, by the amount 01 the loss in the resistance (5. Therefore, it the telephonic currents are properly received at the receiver :i, then the recording level at the recorder S, wh ch is l'iigher than the level at the receiver by the amount o'ij' the lo s in the resistance 6, would be suliicient for satisfactory recording.

It will be understood that the levels here- -inbet'ore described are merely illustrativev and may be varied in practice as conditions may require. 4

It will also be understood that the details of the arrangement herein set forth may be varied and the general principles hereindis closed may be embodied inmany other organizations widely different from that illustrated without departing from the spirit of the invention or the scope of the appended means, the level at the indicating means be sing difierent from the level at the recording means by a predetermined amount,

2. A recording system comprising an electrical circuit, means for transmitting and re- .ceivingvoicecurrents' said electrical circuit, means for amplifying the voicecurrents' in' said electrical circuit,'means for adjusting the gain of said amplifying means, means for-'recording'said voice currents after,

receiving v 'voice currents in said electrical circuit, amplifying means, means forvarying the gain oi said amplifying -me'ans,

. amplifyin amplification, and meansfor reducing the levelof vthe received currents in said electri- 20;

currents may be utilized for indicating the I levelv at said recording means. s 1 3. 'A recording system comprising an elecja ,trical circuit upon which voice currents may,

cal circuit so that the level of said received be superposed, means for transmitting and means for recording said amplified voice currents, and means including an impedance of predetermined magnitude and an audible device for changing the. level of the received currents so as to indicate at said audible de-l vice whether the 7 level at said recordingmeans is suihcient 'for proper recording.-

4. A recordingsystem comprising a telephone loop circuit, means for transmitting and receiving messages oversaid loop circuit, means, recording means, means for adjusting the level of the currents at said recording means for roper' recording, and means for indicating t e level at, said recording means, the level of said indicating means being difi'erent from the level of said-record ing means by I a fixed and predetermined amount.

5. A recording system comprising a telephone circuit. in which fluctuations in the telephonic currents are established in accordance with voice currents, recording means for said telephonic currents, means for ob taining suficient energy at said recording means, and means for indicating when the amount of energy entering said" recording- 'means for amplifyin phone line over w means is sufiicient for proper recording, said indicating mea'ns' being separated from said recording means by an impedance of definite magnitude.

.;6. A recording system comprising a tele- 7 phone circuit, means for transmittin cur,-

ceiving currents in said telephone circuit, an amplifier, a recorder, a potentiometer for varying the gain of said amplifier, the output circuit of said amplifier being associated with the receivingmeans and the recorder,

and a resistance serially' "arranged between the inscribing element of said recorder and said receiving means so that the energy level of said receiving means is fixed with refer-- ence to. the recorder.

'. 7. A-recordingsystem comprising a tale-J phone circuit in which fiuctuationsin the telep'honicpurrents are established in accord;

ance with voice currents, recording means,

I said telephonic currents so as tobe suflicient for. roper record- "to rents in said telephone circuit, means or re- 7 ing, and a resistance associate with the outapplied to said recording meansfor proper recording. J

' '8 A recording siste'mjcom rising a telerecorder as to provide audiblemeans for inich telep onic currents may be transmitted and received, a recorder and a telephone receiver between which an impedance of fixed magnitude is interposed, said telephone receiver being so relat'edtothe ppm; circuitof said amplifying means and arranged serially between the receiver of; said dicating' when the level of energy received by 7 .said recorder'is'sufiicient for good recording.

9; A recording system comprising a telephone hneover which telephonic currents may be transmitted and received, a recorder for said telephonic currents, and audible means'supplied with-current having an ene crgy lev'el less than the energy level at said recorder bya predetermined amount, thus indicating When the level of energy received by said recorder ,is sufficient for good recording.

Intestimon) whereof,'I have signed my name to thisspecifi'cation this 28th day of January,'1925.

. IRVING EVALTER 

